The study is to begin with evaluation of the natural frequency of urinary tract infection and vesicoureteral reflux in the many primate species here. Thus later correlation of bacteriology in the urine with renal pathology at autopsy or biopsy will be possible. The importance of endotoxin produced ureteral malfunction, an obstructive disorder, to the progression of pyelonephritis will be evaluated, since temporary change in ureteral function has been shown to occur from the endotoxin and ureteral obstruction is not only a sigificant factor in the etiology of chronic pyelonephritis but is a frequently used tool for the production of experimental pyelonephritis. The use of the rapid renal scintiscan makes possible evaluation of ureteral function without the diuresis that occurs from the contrast agent during excretory pyelography as necessary even for cine-radiographic studies of ureteral function. In addition measurements requiring surgical exposure of the ureter or manipulative procedures such as ureteral catheterization which may in itself change the function of the ureter are not necessary. The effect of surgically produced vesicoureteral reflux on the progression of disease will be evaluated and the difference in the course of pyelonephritis in the mature and immature monkey will be studied.